This invention relates to devices used with fuel nozzles. In the field of commercial gasoline stations, there is an increased awareness of the dangers of electrostatic discharge around fuel pumps. Electrostatic Discharge (ESD) is often defined as a transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field. For purposes of this application, ESD refers to a rapid transfer of an electrostatic charge, resulting in a spark sufficient to ignite combustible gases. When ESD occurs around a fuel pump, it can ignite the gasoline vapors and start a fire. These fires may, for example, be caused by a person re-entering his or her vehicle during refueling to get warm, or by containers not being filled on the ground. As a result, different devices and methods have been developed to try to safely discharge static charges around fuel pumps.
One method of solving the problem of ESD near a fuel dispensing apparatus places static dissipative signs near the pump for consumers. These signs require the consumer to purposely approach and touch the sign to safely discharge any static charges he or she is carrying. However, if the consumer fails to notice or use the sign, the risk of ESD occurring and starting a fire is still present. It is now common to require that a fuel hose connected to the fuel nozzle be grounded. In theory, static charges are safely dissipated through the hose when the consumer contacts the nozzle or fuel hose, before fueling begins. However, in practice the nozzle and fuel hose are typically covered with insulating materials that may prevent safe discharge of the user, and in any event the consumer may take actions, like re-entering the vehicle, which change his or her electrostatic potential after fueling has begun. Unless the user has previously been grounded, contact by the user with the fuel nozzle or other objects may cause a dangerous spark by ESD.
It is common practice to equip fuel dispensing nozzles with a guard, which is generally a close-fitting elastomeric jacket or cover that is pulled over the nozzle to provide a comfortable handgrip for the nozzle user, and to provide a bumper surface to keep from nicking the finish of vehicles with the nozzle as gasoline is dispensed. The guard is usually formed of a soft plastic material such as vinyl, which may be easily injection molded, or dip molded using a formed mandrel plunged into a vinyl plastisol, wherein the vinyl guard may be then stripped from the mandrel for use on the nozzle. The vinyl compounds used for guards are fairly impervious to gasoline and other contaminants encountered in the field, and may be replaced when damaged.
However, there are some disadvantages to this type of guard. The vinyl compounds can prevent safe static discharge through a grounded nozzle or hose, generally not because they are inherently Insulative, but because they are so thin that they do not prevent sparking between a user and the nozzle. In addition, it is cumbersome to replace the guard because, typically, the nozzle must be disconnected from the fuel pump hose before removal and replacement of the guard. Another disadvantage is that adhesive labels used for information and advertising do not readily adhere to vinyl plastisols. As a result, recent trends to include advertising on nozzles require installation of a second display cover on top of the guard. While the second display covers provide an effective surface for advertising and information, they are usually large, bulky, and comprise multiple parts which complicate installation and replacement of ads.